White accumulation on ladder rails

[tmpfeifer]

I have a 24 foot in ground pool that is half in ground. It has wedding cake steps. I use BBB and my chemical levels are in range per the pool calculator. The pool has wedding cake steps. I have noticed patches of a white substance accumulating on my ladder rails. I'm not really sure what it is. I'm attaching a photo. It's a bit hard to see white on white. Any ideas?
[attachment=0:3euho79v]IMG_1431B.jpg[/attachment:3euho79v]

 

[Bama Rambler]

Post a set of test results, but that looks like scaling. It's odd to see it there. How easy is it to brush off?

Are those plastic rails or aluminum?